In image forming apparatuses, such as copiers, printers and facsimile devices, using the electro-photographic technology, a latent image is formed on the evenly charged surface of a photoconductor by a scanning exposure of an exposure device, such as laser beams.
Said latent image is developed to be a toner image on the photoconductor, and said formed toner image is transferred onto a supporting member, such as an intermediate transfer member or a sheet of recording media, by the function of an electrical field and electrical current which are produced between the transfer member and the photoconductor.
However, it is almost impossible for the image forming apparatus that the toner image formed on the photoconductor is completely transferred onto the supporting member, such as an intermediate transfer member or a sheet of recording media, whereby a small amount of toner particles remains on the photoconductor after the transfer process is completed. In order to remove said residual toner particles on the photoconductor, the cleaning section is provided.
Most cleaning sections have a rotating brush which removes any residual toner remaining on the surface of the photoconductor, and a blade which wipes any remaining toner which still remains after the brushing rotation.
Unexamined Japanese Patent Application Publication No. 10-254,323 discloses that while the rotating brush rotates, it contacts the surface of the photoconductor to remove any residual toner remaining after the transfer operation. Accordingly, the rotating speed is controlled so as not to damage the surface of the photoconductor, nor to firmly fix the toner onto the surface of the photoconductor, due to rubbing on the surface of the photoconductor.
The above blade is generally formed of an elastic resin, such as a polyurethane type resin, whereby its cutting part faces against the moving direction of the surface of the photoconductor, and a surface adjacent to the cutting part is arranged to contact the photoconductor.
Since the blade scrapes the photoconductor through a certain contacting area (hereinafter referred to as a “nipping section”), the blade is electrically charged due to rubbing with the photoconductor.
If the blade, charged to be a certain polarity, contacts any toner particles, which carries polarity opposite that of the blade, said toner particles are captured by the electrostatic force of the blade, and are gradually accumulated.
The accumulated toner particles are shifted to the photoconductor which touches the blade, and are firmly adhered to the surface of the photoconductor. This adhered toner causes further adhesion of toner particles or an external additive, onto the surface of the photoconductor.
Adhered particles, due to the above procedure on the photoconductor, interrupt the exposure process of forming the latent image, so that electrical potential cannot be changed by the exposure on the evenly charged the photoconductor where the adhered particles exist.
Accordingly, toner particles do not adhere onto the section where the adhered particles exist, whereby white spots appear on a developed image as a void image. Such phenomenon is well known as a defect of images, which is sometime called “exclamation mark”.